Sickle Cell Anemia

Context

The U.S. Food and Drug Administration (FDA) has granted approval for two gene therapies for sickle cell disease.

Sickle Cell Anemia

Sickle cell anemia (SCA) is a genetic blood disorder characterized by the presence of abnormal hemoglobin (HbS). HbS is a mutated form of hemoglobin that causes red blood cells to become stiff and sticky, resembling the shape of a sickle or a crescent moon. These sickle-shaped red blood cells have a limited lifespan and can easily block blood flow, leading to various complications.

 Causes

• SCA is an inherited disorder caused by a mutation in the HBB gene, which is responsible for making the beta chain of hemoglobin. This mutation is passed down from parents to children. A child will only develop SCA if they inherit two copies of the mutated gene, one from each parent.

Symptoms

• Fatigue
• Shortness of breath
• Pale skin
• Jaundice (yellowing of the skin and eyes)
• Delayed growth
• Painful episodes (pain crisis) caused by blocked blood flow
• Frequent infections

Diagnosis

• Complete blood count (CBC): This test measures the number and different types of blood cells in the body.
• Hemoglobin electrophoresis: This test identifies the different types of hemoglobin present in the blood.
• DNA testing: This test can confirm the presence of the genetic mutation that causes SCA.

Treatment

• Pain management: Medications such as pain relievers and opioids can help manage pain during pain crisis.
• Hydroxyurea: This medication can help reduce the frequency and severity of pain crisis.
• Blood transfusions: Blood transfusions can help increase the number of healthy red blood cells in the body.
• Bone marrow transplant: This procedure can replace the bone marrow with healthy bone marrow from a donor.
• Gene therapy: This is an experimental treatment that aims to correct the genetic mutation that causes SCA.

Genetic counseling can help couples with a history of SCA understand their risk of having a child with the disorder. Couples can also consider prenatal testing to determine if their unborn child has the SCA gene.